Estimate of heritability of the PennHIP distraction index in working German shepherd dogs in New Zealand

7th International Veterinary Congress

Background: The reported success of the various subjective screening methods and selective breeding programmes against
canine hip dysplasia (HD) has been limited and has often been less than that expected worldwide. It has been previously
suggested that the PennHIP distraction index (DI) is a more reliable predictor of the genotype. Unpublished data report a
moderate estimate of heritability for this trait. This would imply that selection and breeding strategies based on the PennHIP
distraction index would result in more rapid genetic change per generation than current strategies based on subjective hip
scores.
Aim: To investigate the heritability estimate of the PennHIP distraction index in working German Shepherds in a closed
breeding colony.
Methods: An estimate of heritability for the PennHIP distraction index of individual German shepherd dogs were obtained
using a linear animal model. The model included the fixed effects of gender, birth year, birth season, age at scoring and the
random effect of animal and of the sire. The pedigree file included animals recorded between 2002 and 2016. A total of 195
records were available for evaluation.
Results: The estimate of heritability for the PennHIP distraction index in this population of German shepherds was 0.67±0.38
and 0.21±0.32 for the left and the right hips respectively.
Conclusions: The PennHIP distraction index has moderate heritability making it a feasible selection criterion for selective
breeding programs aimed at producing genetic improvement in hip phenotype. However, these findings need to be verified
with further studies in larger populations of breeds at risk.